5,013 research outputs found
Some Thoughts on Terminology and Discipline in Design
In this speculative paper, I will argue that the design community should attempt to develop a “dictionary” of the language of design, along the same lines as the Oxford English Dictionary was and is developed: as a catalogue of the living use of terms. I will sketch an outline of how such a project could be started quite easily with modern technologies. I will then consider one word in particular – “discipline” – as an example of the need for such a dictionary, by examining the various senses of the word and how even just reflecting on that can illuminate issues of clear communications.
Keywords:
Terminology; Lexicography; Semantics; Dictionary; Communication; Language.</p
Towards the quantification of the semantic information encoded in written language
Written language is a complex communication signal capable of conveying
information encoded in the form of ordered sequences of words. Beyond the local
order ruled by grammar, semantic and thematic structures affect long-range
patterns in word usage. Here, we show that a direct application of information
theory quantifies the relationship between the statistical distribution of
words and the semantic content of the text. We show that there is a
characteristic scale, roughly around a few thousand words, which establishes
the typical size of the most informative segments in written language.
Moreover, we find that the words whose contributions to the overall information
is larger, are the ones more closely associated with the main subjects and
topics of the text. This scenario can be explained by a model of word usage
that assumes that words are distributed along the text in domains of a
characteristic size where their frequency is higher than elsewhere. Our
conclusions are based on the analysis of a large database of written language,
diverse in subjects and styles, and thus are likely to be applicable to general
language sequences encoding complex information.Comment: 19 pages, 4 figure
Cascading gauge theory on dS_4 and String Theory Landscape
Placing anti-D3 branes at the tip of the conifold in Klebanov-Strassler
geometry provides a generic way of constructing meta-stable de Sitter (dS)
vacua in String Theory. A local geometry of such vacua exhibit gravitational
solutions with a D3 charge measured at the tip opposite to the asymptotic
charge. We discuss a restrictive set of such geometries, where anti-D3 branes
are smeared at the tip. Such geometries represent holographic dual of cascading
gauge theory in dS4 with or without chiral symmetry breaking. We find that in
the phase with unbroken chiral symmetry the D3 charge at the tip is always
positive. Furthermore, this charge is zero in the phase with spontaneously
broken chiral symmetry. We show that the effective potential of the chirally
symmetric phase is lower than that in the symmetry broken phase, i.e, there is
no spontaneous chiral symmetry breaking for cascading gauge theory in dS4. The
positivity of the D3 brane charge in smooth de-Sitter deformed conifold
geometries with fluxes presents difficulties in uplifting AdS vacua to dS ones
in String Theory via smeared anti-D3 branes.Comment: 47 pages, 6 figures. v2: published version. arXiv admin note:
substantial text overlap with arXiv:1108.607
Entropic analysis of the role of words in literary texts
Beyond the local constraints imposed by grammar, words concatenated in long
sequences carrying a complex message show statistical regularities that may
reflect their linguistic role in the message. In this paper, we perform a
systematic statistical analysis of the use of words in literary English
corpora. We show that there is a quantitative relation between the role of
content words in literary English and the Shannon information entropy defined
over an appropriate probability distribution. Without assuming any previous
knowledge about the syntactic structure of language, we are able to cluster
certain groups of words according to their specific role in the text.Comment: 9 pages, 5 figure
Stacking of oligo and polythiophenes cations in solution: surface tension and dielectric saturation
The stacking of positively charged (or doped) terthiophene oligomers and
quaterthiophene polymers in solution is investigated applying a recently
developed unified electrostatic and cavitation model for first-principles
calculations in a continuum solvent. The thermodynamic and structural patterns
of the dimerization are explored in different solvents, and the distinctive
roles of polarity and surface tension are characterized and analyzed.
Interestingly, we discover a saturation in the stabilization effect of the
dielectric screening that takes place at rather small values of .
Moreover, we address the interactions in trimers of terthiophene cations, with
the aim of generalizing the results obtained for the dimers to the case of
higher-order stacks and nanoaggregates
Simulation of Heme using DFT+U: a step toward accurate spin-state energetics
We investigate the DFT+U approach as a viable solution to describe the
low-lying states of ligated and unligated iron heme complexes. Besides their
central role in organometallic chemistry, these compounds represent a
paradigmatic case where LDA, GGA, and common hybrid functionals fail to
reproduce the experimental magnetic splittings. In particular, the imidazole
pentacoordinated heme is incorrectly described as a triplet by all usual DFT
flavors. In this study we show that a U parameter close to 4 eV leads to spin
transitions and molecular geometries in quantitative agreement with
experiments, and that DFT+U represents an appealing tool in the description of
iron porphyrin complexes, at a much reduced cost compared to correlated
quantum-chemistry methods. The possibility of obtaining the U parameter from
first-principles is explored through a self-consistent linear-response
formulation. We find that this approach, which proved to be successful in other
iron systems, produces in this case some overestimation with respect to the
optimal values of U.Comment: To be published in The Journal of Physical Chemistry B 30 pages, 15
figure
Entanglement and symmetry in permutation symmetric states
We investigate the relationship between multipartite entanglement and
symmetry, focusing on permutation symmetric states. We use the Majorana
representation, where these states correspond to points on a sphere. Symmetry
of the representation under rotation is equivalent to symmetry of the states
under products of local unitaries. The geometric measure of entanglement is
thus phrased entirely as a geometric optimisation, and a condition for the
equivalence of entanglement measures written in terms of point symmetries.
Finally we see that different symmetries of the states correspond to different
types of entanglement with respect to SLOCC interconvertibility.Comment: 4 pages, 2 figures. Preliminary versions of some of these results
were presented in the QIT 16 workshop in Japan, D. Markham, Proceedings of
QIT 16, Japan (2007). Updated to reflect changes for publication: expanded
proofs and some new examples give
Quantum Quenches in Free Field Theory: Universal Scaling at Any Rate
Quantum quenches display universal scaling in several regimes. For quenches
which start from a gapped phase and cross a critical point, with a rate slow
compared to the initial gap, many systems obey Kibble-Zurek scaling. More
recently, a different scaling behaviour has been shown to occur when the quench
rate is fast compared to all other physical scales, but still slow compared to
the UV cutoff. We investigate the passage from fast to slow quenches in scalar
and fermionic free field theories with time dependent masses for which the
dynamics can be solved exactly for all quench rates. We find that renormalized
one point functions smoothly cross over between the regimes.Comment: 40 pages; v2: a bit late, but it includes minor modifications to
match published versio
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